Pretty simple actually. As you approach max visual range from target watch from either nose turret, or external view.
When you can see the target line the plane up so it will overfly the target.
Go calibrate.
The better job you do of lining up the more options you have.
This includes figuring out optimum attack angles, IP points, etc.
In effect by going to F3 external mode, zooming out, you turn the plane into its own pointer.
Showing you where it is going to go.